1. Field of the invention
This invention relates to an air dryer unit comprising an air dryer and an air storage tank which unit is adapted for use in a pneumatic circuit for an air brake or the like of a vehicle.
2. Prior Art
Dried compressed air is used for operating a pneumatic circuit. A system for producing such dried compressed air comprises an air dryer device for removing the moisture of compressed air, fed from an air compressor, to dry it, an air tank for storing the dried compressed air, and a purge tank disposed between the air dryer device and the air tank for storing the compressed air for regenerating a desiccant of the air dryer device.
The air dryer device comprises a dryer containing the desiccant for drying the compressed air, and generally the purge tank is vertically mounted on the dryer and connected thereto to provide a unitary construction. Thus, such a construction has a relatively large dimension in the vertical direction. This imposes limitations on a space for accommodating such an air dryer construction. One method of overcoming this difficulty is to provide the air dryer device and the purge tank separately. However, this approach is disadvantageous in that the installation of the air dryer unit requires more time and labor.
There has been proposed in Japanese Utility Model Publication No. 57-47056 an air dryer unit in which the purge tank is provided separately from the air dryer device and in which the purge tank is formed integrally with the air tank. This conventional air dryer unit is still found not entirely satisfactory in the time and labor required for its installation.